微系统中转矩及电渗流作用下的微粒子电动旋转操控  

Electrorotation manipulation of microparticles induced by torque and electroosmotic slip in microsystem

作　　者：姜洪源[1,2] 任玉坤[1] 陶冶[1] 

机构地区：[1]哈尔滨工业大学机电工程学院,哈尔滨150001 [2]浙江大学流体传动及控制国家重点实验室,杭州310027

出　　处：《物理学报》2011年第1期142-150,共9页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:51075087);浙江大学流体传动及控制国家重点实验室基金(批准号:GZKF-201004);国家留学基金(批准号:2009612129)资助的课题~~

摘　　要：微粒子的电动旋转操控是表征分散系中微粒子介电特性的有效方法.低雷诺数微系统中,以Maxwell-Wagner极化理论为基础,进行了转矩作用下的微粒子电动旋转机理研究,推导了此机理作用下微粒子电动旋转峰值速度所对应的特征频率,分析了弛豫时间对粒子旋转方向的影响,对转矩作用下的微粒子电动旋转速度进行仿真;以双电层理论为基础,对电渗流导致的微粒子电动旋转机理进行定性分析,提出具有金修饰的粒子表面更适合电渗流作用下的电动旋转研究.分别以羧基修饰的聚苯乙烯微球以及表面被金修饰的聚苯乙烯微球为操控对象,进行电动旋转实验研究.结果表明,羧基修饰的聚苯乙烯微球电动旋转方向与电场相反,其速度峰值对应频率较高,转矩起主导作用;而表面被金修饰的聚苯乙烯微球电动旋转方向与电场相同,其速度峰值对应频率较低,电渗流起主导作用.Electrorotation is an effective technique to characterize the electrical properties of dispersed particles. For the low Reynolds number microsystem,the mechanism of the electrorotation of microparticles induced by torque was analyzed based on the Maxwell-Wagner polarization. Characteristic frequency corresponding to the peak value of the electrorotation speed was deduced and the effect of the relaxation time on the particles′ electrorotation direction was analyzed by the simulation of the electrorotation speed induced by the torque. The mechanism of the electrorotation of the microparticles induced by electroosmotic slip was qualitative analyzed based on the double layer and the idea about the gold surface being favorable to the electrorotation was proposed. Experiments on the electrorotation of the polystyrene with the carboxy surface and gold modified surface were performed,respectively. The results show that,the direction of the electrorotation of polystyrene spheres with carboxy surface is opposite to the electric field and,the corresponding frequency is higher with the torque playing the leading role. On the other hand,direction of the rotation of polystyrene spheres with the gold surface is homodromous with the electric field and the corresponding frequency is lower with the electroosmotic slip playing the leading rose.

关 键 词：微系统 电动旋转 转矩 电渗流 

分 类 号：O361.4[理学—流体力学]